1. Field
Embodiments of the present disclosure relate generally to metal production and, in certain embodiments, relates to methods of producing metallic tubular bars having high toughness at low temperature while concurrently possessing sulfide stress corrosion cracking resistance. Certain embodiments relate to heavy wall seamless steel pipes for risers, line pipes and flow lines for use in the oil and gas industry, including pipes that are suitable for bending.
2. Description of the Related Art
Exploration of offshore oil and gas reserves in remote regions of the world is increasingly moving away from conditions where relatively traditional pipe solutions can be utilized and towards more demanding environments. These more demanding environments may incorporate a combination of very challenging factors, including for example, deep water locations, increased pressure and temperature wells, more corrosive products, and lower design temperatures. These conditions, when added to stringent weldability and toughness criteria already associated with pipe specifications for offshore oil and gas exploration applications, place ever increasing demands on the materials and supply capability.
These demands are evident in project developments involving aggressive composition and high operating pressure that require very thick wall, sour service carbon steels. For example, major seamless line pipe manufacturers are able to manufacture pipes of grades X65 and X70 according with American Petroleum Institute (API) 5L and International Organization for Standards (ISO) 3183 standards, with sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) resistance, when wall thickness (WT) is below 35 mm. However, the conflicting requirements of strength and toughness, combined with the need for sulfide stress corrosion (SSC) and hydrogen induced cracking (HIC) resistance (e.g., sour resistance) in thick wall pipes (e.g., WT greater than or equal to 35 mm) has proven difficult to achieve.
In the complex scenario of line pipe projects for applications such as sour service, deep and ultra-deep water, Arctic-like areas, etc., heavy wall bends have also become an important feature of pipes.